The present invention concerns a method of arranging an inspection hole in cable joints of the kind comprising a clamping sleeve of essentially circular or oval cross-sectional shape and consisting of metal, a metal alloy, or a synthetic material, the clamping sleeve being provided with a preformed conical end portion or with a cylindrical end portion arranged to be shaped into conical configuration, the clamping sleeve being arranged, when compressed, to lock a cable end section which has been passed through the sleeve and positioned in a loop, with the cable end passed back into the sleeve, the clamping sleeve being provided with an opening in the end portion or the transitional zone intermediate the cylindrical sleeve portion and the conical end portion before compressing of the clamping sleeve.
It is previously known to provide clamping sleeves of this kind with a notch or opening whereby it becomes possible to check that the cable end is inserted sufficiently far into the sleeve. Prior art methods do not, however, function satisfactorily. In accordance with one prior art structure, the inspection hole is comparatively small, and as a result the position of the cable end inside the sleeve may be checked only before the clamping sleeve is compressed. During the compression of the sleeve, the opening often closes and, as a result, the final position of the cable end inside the clamping sleeve cannot be established with certainty.
In another prior art structure, the clamping sleeve is provided with a comparatively large indentation or notch which does not close completely during the compression of the clamping sleeve, and this structure therefore makes it possible to check the cable end position in the clamping sleeve after compression of the latter. However, during the compression of the sleeve, which is made from a plastic material, uncontrollable flow of material occurs in the sleeve, particularly in the marginal areas of the notch, and such flow may easily cause fissures, which extend in the longitudinal direction of the sleeve, and consequently the strength thereof is considerably reduced.